Colorimeters can be used to test water quality by screening for chemicals such as fluoride, chlorine, cyanide, dissolved oxygen, iron, zinc, phosphorus, calcium, silica, bromine, ammonia, and more.

Colorimeters are used to find the concentration of a substance in a solution, based on the intensity of the color in the solution. If the solution that is to be tested is a colorless liquid, a reagent is added that reacts with the liquid, producing a color. Colorimeters measure the absorbance of wavelengths of light at a particular frequency (color) by a sample utilizing the Beer-Lambert’s law.